This invention relates in general to universal joints and in particular to an improved structure for positively retaining the bearing cups on the trunnions of a universal joint cross prior to assembly into a vehicle.
Universal joints are well known devices that provide a driving connection between two members adapted to rotate about non-aligned axes of rotation. Universal joints are widely used to connect rotatable members in vehicle drive train systems. In a typical drive train system, a first universal joint is connected between an output shaft of an engine/transmission assembly and a first end of a driveshaft tube, while a second universal joint is connected between a second end of the driveshaft tube and an input shaft of an axle assembly. The universal joints provide a rotational driving connection from the output shaft of the engine/transmission assembly through the driveshaft tube to the input shaft of the axle assembly, while accommodating a limited amount of misalignment between the rotational axes of these three shafts.
A typical structure for a universal joint includes a cross having a central body portion with four cylindrical trunnions extending outwardly therefrom. The trunnions are oriented in a single plane and extend at right angles relative to one another. A hollow cylindrical bearing cup is mounted on the end of each of the trunnions. Needle bearings or similar means are provided between the outer cylindrical surfaces of the trunnions and the inner cylindrical surfaces of the bearing cups to permit relative rotational movement therebetween. The bearing cups mounted on a first opposed pair of the trunnions are connected to a first yoke which, in turn, is secured to one of the rotatable components of the vehicle drive train system. Similarly, the bearing cups mounted on a second opposed pair of the trunnions are connected to a second yoke which, in turn, is secured to a second one of the rotatable components of the vehicle drive train system.
Frequently, the first and second universal joints are manufactured concurrently with the driveshaft tube at a first location, then shipped as a unit to a second location for assembly with the other components of the vehicle drive train system. In such a manufacturing process, yokes are initially secured to the ends of the driveshaft tube, then a universal joint is connected to each of the yokes. Thus, for each of the universal joints, only one opposed pair of the bearing cups is connected to a yoke and, therefore, positively retained on the respective trunnions. The other opposed pair of the bearing cups remains mounted on the respective trunnions, but is not positively retained thereon. Following installation on the yokes, each of the universal joints is purged with lubricant. Such purging is well known in the art and involves the injection of lubricant within the cross at a relatively high pressure. The lubricant passes through bores formed through each of the trunnions so as to move into the regions of the bearings disposed between the bearing cups and the trunnions.
It is known to provide elastomeric seals about the open ends of the bearing cups to retain lubricant in the region between the outer surface of the trunnion and the inner surface of the bearing cup where the roller bearings are located. The elastomeric seals also function to prevent the entry of dirt and other contaminants into the regions where the roller bearings are located. Additionally, it is known to provide rigid dust guards about the open ends of the bearing cups to protectively cover the elastomeric seals, and further to prevent the entry of dirt and other contaminants into the regions where the roller bearings are located. In some instances, the elastomeric seal and rigid dust guard have been combined into a single seal and dust guard assembly.
In the past, the rigid dust guards have been utilized to retain the bearing cups on the trunnions during shipment from the manufacturing facility to the assembly facility, as described above. To accomplish this, it is known to form the dust guard having a first portion that frictionally engages the outer surface of the trunnion and a second portion that engages an annular groove formed in the outer surface of the bearing cup. Although this structure has been generally effective, it has been found that the bearing cups can still become dislodged during shipment if a large impact is applied thereto. Even if the bearing cups are not removed from the trunnions as a result of these impacts, they may become misaligned therewith. Such misalignment is undesirable because it can result in non-uniform sealing pressures being exerted against the trunnions, resulting in non-uniform lubricant injection during the purging process. Thus it would be desirable to provide an improved structure for positively retaining the bearing cups on the trunnions of a universal joint cross prior to assembly.